Pump question

[oneness]

In looking at the specs for my pump, I have a couple questions. The pump is made by Interpump, from Italy, and the model number is WS202. The specs on the pump are metric, and show it to be 21 litres per minute, and 200 bar. The conversions I have are litres/3.79=gallons, which gives me 5.5 gallons per minute, and bar*14.5=psi, which gives me 2900psi.

Are these conversions correct? If so, I'm short 100psi from what the machine was advertised as (I bought it used).

The 2nd issue I have is the gpm...The machine was advertised at 5.5 gpm, and my numbers back that up. However, I'm only pulling just a hair under 5 gallons. I've checked my connections between the tank and the pump, and I have no leaks. I haven't hooked the supply hose up directly to the pump yet, that's my next step. My question is, what are the possible causes of a loss of gpm, other than the engine/pump running slower than they should.

Last question, how can I check that the engine/pump are turning at the proper speed?

Thanks!

 

[Mark]

The Interpump WS202 is pretty much the same pump as the General TS2021, General Pump is owned by Interpump.

I have yet to see that pump deliver its rated 5.6 GPM even when it is force fed, typically you should get around 5.0 to 5.2 GPM out of that pump when turning it at 1450 RPM.

You can use an engine tach to check your engine rpm and then figure out your pulley ratio to determine your pump speed.

With a strobe type tach you can probably determine your pump RPM by making a mark on the pulley.


Feel free to calll me Monday I will try to help you out.

 

[oneness]

Another question....

what is to stop me from installing a larger pulley? For example, one large enough to deliver 20% higher rpms on the pump....Which should give me 20% higher gpm and psi....Would this damage the pump, and if so, why?

 

[Mark]

Turning the pump faster than 1450 RPM is NOT recomended,
higher RPM will increase nthe GPM but the PSI is not determined by RPM.

What engine are you running with that pump? Hot water unit? if so 12 volt or generator?

 

[Larry L.]

You want a smaller pulley for more at the pump.

I did it on a 310 cat pump,ran it several years without any damage,not saying you'll be as lucky with a General,don't know.

 

[oneness]

What determines the psi, if not the pump? I realize the unloader (I have a flow type) plays a factor also...In other words, is it possible to adjust the psi upwards on a pump, and if not, why?

Thanks, Bigboy...wasn't thinking clearly on that one...

 

[Mark]

Mike,

You can achieve the rated PSI or more when turning
pump at its rated RPM, PROVIDING you have ample power (horsepower).

I do not suggest you run a pump at more than its rated RPM or pressure, unless you first get an OK from the manufacturer.

Larry has been lucky with his Cat pump.

 

[oneness]

My question was, why can't you increase the psi by increasing the rpms? I realize that this may not be a good idea, but I'd like to understand the principle of this, not just whether it is good or bad. I also realize that you have to have sufficient HP to achieve the desired psi and gpm.

that brings me to another question...the specs on the pump say that 10 hp is required...but the charts I've seen say that 18 is required for 5.5gpm and 3000 psi.

 

[Larry L.]

I know the pulleys aren't cheap and in my case you cann't take them back after ordering.Try going a 1/2 in. smaller you can always put your old one back on OR go smaller.Marks right it takes a little more horsepower to pull the smaller pulley,I was running a 16 hp.Cat is a tuff pump,it will go though alot, I've never liked the Generals b/c I had trouble with the V-packing not lasting,a smaller pulley could be damaging on a general,don't know.

O.....most pumps will do more than they are rated,it protects the maker.

 

[oneness]

Well, the first thing I want to do is assure that everything is working properly, and that the best I can expect is 2800psi and a hair under 5gpm...Hell, that's not much better than a $1000.00 home depot machine.

 

[Mark]

The horsepower requirements on the pump are for an electric motor not a gas engine.

Here are some links to some valuable pump information check them out, they may help answer some of your questions.

http://generalpump.com/cPump_basics.asp

http://generalpump.com/cTrouble_shooting.asp

http://generalpump.com/cFAQ.asp

http://www.arnorthamerica.com/pumpeducation.html

http://www.arnorthamerica.com/handyformulas.html

Follow the above links to get a quick education on pumps etc.

 

[oneness]

Thanks, Mark! I'll do just that this evening!

 

[oguard]

The PSI rating of any pump is based on the ability of the weakest component of the pump to withstand the pressure over a given time without failing. In other words it is the ability of the pump to resist the forces of the pressure. Where does the pressure come from? I will get to that in a moment.

Every piston or wobble plate pump is a positive displacment system. Every stroke of the piston will displace the same amount of water. RPM will determne how many of these units of volume will be pumped. Engineers determine the safe effective working parameters for all of the moving components based on longevity of the components and their ability to withstand the stresses imposed by moving an incompressible fluid. Essentially what you have is a hydraulic pump.

All pumps are rated at a set RPM to provide rated GPM/Litres. They also allow for a +/- of 10% minimum and still considered within specification. They are also rated without a nozzle in place.

Now where does the pressure come from? Have you ever put your thumb over the end of your garden hose to get more power? Well, the tip provided by the manufacturer is nothing more than a piece of hardened steel with a very precise hole in the end to provide resistance to flow, therefore increasing the pressure. Using a soap nozzle will demonstrate the pressure lowering available from a larger orifice.

The nozzle chart will show you what your 'actual' GPM and pressure are for a given orifice. Refer to the excellent chart here

http://www.arnorthamerica.com/spraynozzlechart.html

to see what the different sizes will give.

Over-speeding a pump will lower it's life expectancy and void all warranties.

For future conversion reference please use the following formulae...

1 bar = 14.5038 PSI

1 litre = 0.264 US Liquid gallons

1 US Liquid gallon = 3.7854 litres

Hope this helps? Cheers.

 

[Mark]

Michael,

Thanks I could not have said it better myself.

 

[Larry L.]

You can hold your thumb on a garden hose to get your psi,altho after adding a little more gpm you'd have to get a bigger thumb to let more psi out of the hose.I'm not saying its ok to speed up the pump nor am I saying to over rib the pump in rpm's.Like most women,they can handle a little more than what you have,you can over do anything,then again I guess it depends on how big the thumb is holding the garben hose .